Our earlier work showed that the dorsal columns of the monkey were critical for discrimination of the spatiotemporal features of tactile stimuli; we then asked whether this specialized role is reflected by similar specialization in the somatosensry cortex, particularly areas 2, 5 and 7. Incomplete results on 14 monkeys suggest that lesions in these posterior parietal regions impair tactile spatiotemporal performances more than simple tactile discrimination which do not depend on the integrity of the dorsal columns. Lesions in areas 3 and 1 produce severe deficits in both tasks. We tentatively conclude that dorsal column information is transmitted to areas 3 and 1 together with the information carried by the other lemniscal and non-lemniscal cutaneous pathways, but the former signals then become segregated and relayed to the posterior regions for further processing. In another study with 3 monkeys, morphine disrupted the discrimination of innocuous skin warming and cooling; lower doses affected only skin warming. These results suggest a preferential effect of analgesics on small-fiber sensory systems and not on pain exclusively. To determine the extent to which temperature and pain mechanisms share common features, we will attempt to develop a behavioral model for measuring pain tolerance and temperature discrimination contemporaneously in primates, and then assess the effects of intracerebral manipulations on both sensory functions.